‘In all that time we have never heard of anything like that happening. It’s just unacceptable behaviour. I won’t stand for it.’

Parent Lindsey Morgans, 42, of Southsea, was scared by the news and hoped the bus route could be temporarily changed.

‘It’s shocking and really worrying that someone could do this,’ she told The News.

While another parent, who asked not to be named, said the incident was isolated and that there had been no previous attacks.

They added: ‘Children deserve to be protected. To be attacked like that is just disgraceful. I can’t imagine why anybody would want to do that.’

City council boss Donna Jones is hopeful the culprits will be apprehended.

‘This was a very disturbing and traumatic event for the children involved,’ she said.

‘Thankfully there is CCTV in Holbrook Road and I hope police will be able to access the footage to ascertain who carried out this unprovoked and potentially dangerous attack on a group of innocent children going home.’

The school’s headteacher Rebecca Parkyn said police were already hunting for the yobs.

‘We have all been very shocked by this incident but fortunately no-one was hurt,’ she added.

A spokeswoman from Hampshire Constabulary confirmed the force was investigating the attack.